Control system for automatic transmission

Abstract

A control system for an automatic transmission including a main transmission and a subtransmission whose shift operation is carried out by hydraulically. The control system comprises a first device for adjusting a gear ratio advance of the main transmission, the gear ratio advance corresponding to a gear ratio change during the shift operation, a second device for adjusting a gear ratio advance of the subtransmission, the gear ratio advance corresponding to a gear ratio change during the shift operation, and a device for controlling the frist adjusting device and the second adjusting device during concurrent shift operations of the main transmission and the subtransmission so that the gear ratio advances of the main transmission and the subtransmission become equal to respective predetermined target gear ratio advances.

What is claimed is: 
     
       1. A control system for an automatic transmission including a main transmission and a subtransmission whose shift operation is carried out hydraulically, said control system comprising; first means for adjusting a gear ratio advance of the main transmission, said gear ratio advance corresponding to a gear ratio change during the shift operation;   second means for adjusting a gear ratio advance of the subtransmission, said gear ratio advance corresponding to a gear ratio change during the shift operation; and   means for controlling said first adjusting means and said second adjusting means during concurrent shift operations of the main transmission and the subtransmission so that the gear ratio advances of the main transmission and the subtransmission become equal to respective predetermined target gear ratio advances.   
     
     
       2. A control system as recited in claim 1 wherein the gear ratio advance of whichever of the main transmission and the subtransmission which has the larger rate of the gear ratio advance in an initial part of the shift operation of the main transmission and the subtransmission is made larger than that of the other. 
     
     
       3. A control system as recited in claim 1 further comprising means for detecting engine load, and means for adjusting the gear ratio advances in accordance with the dectected engine load. 
     
     
       4. A control system as recited in claim 1 further comprising means for detecting engine torque, and means for adjusting the gear ratio advance in accordance with the dectected engine torque. 
     
     
       5. A control system as recited in claim 1 further comprising means for detecting a ratio between the ratio of gear ratios in the main transmission and the ratio of gear ratios in the subtransmission, and means for adjusting the gear ratio advances in accordance with the detected ratio. 
     
     
       6. A control system as recited in claim 1 wherein each shift operation is carried out in an initial region, an intermediate region and a final region, the shift operation of both the main transmission and the subtransmission being carried out in the intermediate region, and the shift operation of the main transmission being carried out in the initial region and the final region. 
     
     
       7. A control system as recited in claim 1 wherein said predetermined target gear ratio advances are adjusted based on an accelerator opening. 
     
     
       8. A control system as recited in claim 1 wherein said predetermined target gear ratio advances are adjusted based on an altitude at which a vehicle runs. 
     
     
       9. A control system as recited in claim 1 wherein said predetermined target gear ratio advances are adjusted based on an operating condition of an air conditioner. 
     
     
       10. A control system as recited in claim 1 wherein said predetermined target gear ratio advances are adjusted based on the kind of gasoline a vehicle is running on.